So I had a 2008 server that was correctly sending alerts. I reimaged the server using our standard procedure built using the PSP 8.25cd, set our SNMP traps, turned off the windows firewall, etc. when I send a test trap from the HP Software on the server itself, i get the generic test trap on HP SIM. If I reboot that server, I get no notifications in HP Sim other than a ton of Link Up notifications.I've tried deleting and readding the server from HP SIM as well. I've also tried updating the HP software using 8.30 PSP cd.I don't get any system unreachable notifications or anything. This is very odd and I don't know what is going on.

System unreachable is not from an SNMP trap it's triggered by the Hardware Polling task.If the server reboots in between HW polling tasks it will not be caught. You can reduce the interval the HW polling task runs.